[PATCH v3 0/6] Enable gpu switching on the MacBook Pro

[Lukas Wunner]

The pre-retina MacBook Pro uses an LVDS panel and a gmux controller
to switch the panel between its two GPUs. The panel mode in VBIOS
is notoriously bogus on these machines and some models have no
VBIOS at all, so the inactive GPU cannot set up its LVDS output.

Extend vga_switcheroo to support switching only the DDC lines.
Introduce a drm_get_edid_switcheroo() helper which uses this feature.
Amend i915, nouveau and radeon to call it for LVDS connectors.

This only enables EDID probing on the pre-retina MBP (2008 - 2013),
and only under the condition that apple-gmux loads before the DRM
drivers. Later patches will address reprobing of the DRM drivers
if apple-gmux loads late.

The retina MBP (2012 - present) uses eDP and is apparently not
capable of switching AUX separately from the main link.
This will also be addressed in later patches.


Previous installments:
v1: http://lists.freedesktop.org/archives/dri-devel/2015-April/081515.html
v2: http://lists.freedesktop.org/archives/dri-devel/2015-August/088156.html


Changes since v2:
  * Previously the DDC locking happened in drm_get_edid() and thus
    was done for all DRM drivers, regardless if they are ever used
    on muxed machines. Now this is moved to a separate helper which
    is only called by relevant drivers and only for LVDS connectors.
    (Suggested by Thierry Reding and seconded by Alex Deucher and
    Daniel Vetter.)
  * Squashed commits, overhauled locking, added kernel-doc for new
    public functions and locks.
    (Suggested by Daniel Vetter.)


Thanks a lot to the reviewers and testers for your valuable feedback.


Lukas Wunner (6):
  vga_switcheroo: Add support for switching only the DDC
  apple-gmux: Add switch_ddc support
  drm/edid: Switch DDC when reading the EDID
  drm/i915: Switch DDC when reading the EDID
  drm/nouveau: Switch DDC when reading the EDID
  drm/radeon: Switch DDC when reading the EDID

 drivers/gpu/drm/drm_edid.c                  | 26 ++++++++
 drivers/gpu/drm/i915/intel_lvds.c           |  3 +-
 drivers/gpu/drm/nouveau/nouveau_connector.c | 13 +++-
 drivers/gpu/drm/radeon/radeon_connectors.c  |  4 ++
 drivers/gpu/vga/vga_switcheroo.c            | 98 ++++++++++++++++++++++++++++-
 drivers/platform/x86/apple-gmux.c           | 23 +++++++
 include/drm/drm_crtc.h                      |  2 +
 include/linux/vga_switcheroo.h              |  9 +++
 8 files changed, 173 insertions(+), 5 deletions(-)

-- 
1.8.5.2 (Apple Git-48)